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Fused N-Heterocycles with Contiguous Stereogenic Centers Accessed by an Asymmetric Catalytic Cascade Reaction of Tertiary Enamides |
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| Authors: | Li Zhen Prof. Shuo Tong Prof. Jieping Zhu Prof. Mei-Xiang Wang |
| Affiliation: | 1. Key Laboratory of Bioorganic Phosphorous and Chemical Biology (Ministry of Education), Tsinghua University, Beijing, 100084 P. R. China;2. Laboratory of Synthesis and Natural products, Institute of Chemical Sciences and Engineering, Ecole Poltechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland |
| Abstract: | We report in this article a cascade reaction strategy for the synthesis of complex N-heterocyclic compounds with contiguous and tetrasubstituted stereogenic carbons. Under the sequential catalysis of a chiral binol–Ti complex and BF3, cyclopentanone-derived tertiary enamides undergo an enantioselective enamine addition to ketone carbonyls followed by diastereoselective trapping of the resulting acyliminiums by electron-rich aryl moieties to furnish four- and five-membered ring-fused N-heterocyclic products as the sole diastereomers in high yields with up to 99 % ee. |
| Keywords: | alkaloids asymmetric synthesis cascade reactions cyclization tertiary enamides |